I accused you of nothing by inference or otherwise. I made no inference as it relates to your mindset, but you have to admit a defense of "Why would someone steal only one, why not steal them all" is childlike at best.

What we are talking about here is the theft, or assumed theft, of personal property. Cars, CDs, DVDs, or anything else is still personal property, and the only clear differences here are opportunity and ability.

At the end of the day the OP's son was missing a DVD, and he places the blame, corectly or not, squarely on TSA. An agency so wrapped in bad press lately is going to draw those that as you say "cry wolf" there is nothing to be done about it until this agency changes it's habits and perceptions.

TSA's policies and practices open the agency to this kind of finger pointing. Short sighted policies, such as demanding unlocked baggage, can, have, and will show how disconnected TSA is from reality. When baggage is unlocked it provides an open invitation for crimes of opportunity. Whether a TSA employee stole the DVD, lost the DVD, neglected to repack the DVD, or an airline employee baggage handler did any of the same, the fault still lays on the policy of not allowing the OP's son to properly secure his checked baggage.